The present invention relates to heat exchangers and more specifically relates to a heat exchanger tube support for supporting a plurality of heat exchanger tubes within a heat exchanger.
As known in the art, a heat exchanger transfers heat from a relatively high temperature fluid to a relatively low temperature fluid. Typically, the heat exchanger includes a cylindrical conduit of considerable length having a plurality of tubular heat exchanger tubes supported therein. For the most part, the tubes are straight and extend parallel to a longitudinal axis of the conduit for the length of the conduit. However, the heat exchanger may include a plurality of conduits sequentially interconnected at their ends by hairpin conduit portions with a bundle of tubes within one conduit connected to a successive bundle in an adjacent conduit by a hairpin tube portion.
A conventional heat exchanger operates with a first fluid circulating through a path within the conduit defined by the heat exchanger tubes. A second fluid flows in a longitudinal direction through the conduit and in contact with the tubes. Heat is transferred from the hotter fluid through the tubes to the cooler fluid as the hotter fluid contacts surfaces of the heat exchanger tubes.
The heat exchanger tubes are normally arranged within the heat exchanger conduit in a spaced, parallel relationship relative to one another. However, due to the length of the heat exchanger conduit, the tubes arranged therein tend to sag or bend. In order to maintain the spaced, parallel relationship among the tubes, the tubes are braced at intervals along the longitudinal axis of the conduit.
In known heat exchangers, the tubes are supported at each interval by a circular plate having a diameter substantially equal to the inside diameter of the conduit and extending in a plane perpendicular to the longitudinal direction of flow of the second fluid. The plate has apertures through which both the tubes and the second fluid pass. This type of tube support, however, reduces the efficiency (i.e., the percentage of heat transferred) of the heat exchanger by restricting the flow of the second fluid through the conduit. In order to reduce the flow restrictions associated with these plates, peripheral portions of the plates are cut away to partially eliminate obstructions to the flow of the second fluid. This solution, however, creates a serpentine flow of the second fluid about an outer periphery of the bundle of heat exchanger tubes wherein radially inward portions of the tubes are not freely contacted by the flow of the second fluid. Instead, pools of relatively stationary fluid tend to form at various places in the heat exchanger. The serpentine flow thus inhibits the free flow of the second fluid through the conduit and decreases the efficiency of the heat exchanger.
In order to increase the efficiency of the heat exchanger, a support for the tubes should maximize areas of contact between the flow of the second fluid and the tubes, while minimizing the flow restrictions encountered by the second fluid. Therefore, the support for the tubes should maintain the tubes in a spaced, parallel relationship within the conduit to maximize the contact between the second fluid and the tubes. Further, a support for the tubes should separate the tubes from the inside walls of the conduit and from adjacent tubes, thereby enabling the second fluid to contact substantially all of the exterior surface of each tube. The support should also provide a rigid support which resists any movement of the tubes within the support and which resists any movement of the bundle of tubes within the conduit. However, all of these objectives should be accomplished without unduly restricting the flow of the second fluid through the conduit. Consequently, in positioning the tubes within the conduit, the supports should have a configuration which presents a minimal surface area in a plane perpendicular to the direction of flow, so as not to unnecessarily obstruct the flow of the second fluid through the conduit.
A known heat exchanger tube support is disclosed in U.S. Pat. No. 3,144,081 issued to Skiba and assigned to the assignee of the present invention. Briefly, that support includes a central tubular member which radially supports a first set of three identical V-shaped channel members each having two outwardly diverging sidewalls. A second set of three smaller identical V-shaped channel members with smaller outwardly diverging sidewalls is also secured about the central member. Each smaller channel member is alternately disposed relative to each channel member of the first set. A central tube is received within the central member and six outer tubes are radially supported in a spaced, parallel relationship about the heat exchanger tube support. Each outer tube occupies a separate area defined by the diverging sidewalls of each V-shaped channel member. A band wrapped around the bundle of tubes secures the tubes to the support. The diverging sidewalls of the first set of channel members extend from the central member to the inside wall of the conduit to space the heat exchanger tubes from the inside wall of the conduit.
In the heat exchanger tube support of the Skiba patent, however, the heat exchanger tube support includes seven distinct elements (i.e., one central tubular member, three V-shaped channel members of the first set, and three V-shaped channel members of the second set) in order to support the six outer tubes and one central tube of the heat exchanger. Each of these seven elements must be secured together at six connection points. Further, of the seven elements, there are three separate configurations necessitating three manufacturing processes to produce each configuration.
Other supports for heat exchanger tubes are known. For example, heat exchanger tube supports are disclosed in U.S. Pat. No. 3,134,432 issued to Means; U.S. Pat. No. 3,239,426 issued to Waine et al; U.S. Pat. No. 3,858,646 issued to Naylor; U.S. Pat. No. 4,265,301 issued to Anderson; and U.S. Pat. No. 4,320,566 issed to Boyer et al.
A general object of the present invention is to provide a heat exchanger tube support which overcomes the disadvantages associated with known heat exchanger tube supports.
Another object of the present invention is to provide a heat exchanger tube support which is less expensive to manufacture and less difficult to assemble than known heat exchanger tube supports.
Still another object of the present invention is to provide a significantly simplified heat exchanger tube support which is formed from sets of identical elements.
A further object of the present invention is to provide a heat exchanger tube support which maintains the heat exchanger tubes in a spaced, parallel relationship within a conduit of a heat exchanger.
It is a further object of the present invention to provide a heat exchanger tube support which provides a rigid support for the tubes within the support and the bundle of tubes within the conduit.
A still further object of the present invention is to provide a heat exchanger tube support which does not unduly restrict the flow of fluid within the heat exchanger.
These and other objects and advantages will become apparent to those skilled in the art upon reading the following detailed description of the preferred embodiment of the present invention.
A heat exchanger tube support according to the present invention supports a plurality of heat exchanger tubes in a conduit of a heat exchanger. The heat exchanger tube support includes three elements each being a strip of material defining a projection at a mid-section thereof. Two leg sections extend from the projection and a channel is defined between each leg section and the projection. An attachment mechanism secures the elements together with each leg section of each element being secured to a leg section of an adjacent element, with each leg section extending radially outward and with the channels on each element opening radially outward. In an assembled condition, the elements together enclose an interior area within the heat exchanger tube support.
In a preferred embodiment, each channel is adapted to receive at least one heat exchanger tube and the projections and leg sections are adapted to separate individual heat exchanger tubes within adjacent channels. The leg section of each element extends to the inside wall of the conduit to space the heat exchanger tubes from the inside wall of the conduit.